The absorption band shapes of the combined optical quantum transitions when circularly polarized radiation under conditions of optical orientation and spin polarization creates a two-dimensional exciton in the quantum well structure and simultaneously excites one of the resident electrons from the lowest to the first Landau level are investigated. The light absorption is described in the frame of dipole-active transitions in the second order perturbation theory taking into account the perturbations the electron-photon interaction and the electron-electron Coulomb interaction. The Hamiltonian of the electron-photon interaction depends on the directions of the light propagation and its circular polarizations relative to the magnetic field direction and the electron-heavy-hole alignment in the plane of the layer. The electrons are considered in the s-type conduction band and the heavy holes with orbital momentum projections M = ±1 in the p-type valence band. If numbers of the Landau levels of the e-h pair is the same, ne = nh, the quantum transition is dipole-active. If these numbers differ by unity, the transition is quadrupole-active. In agreement with the experimental observation it is found that if σ− polarized photon creates an electron with the same spin orientation as the resident electrons, they equally participate in quantum transition, so that the probability and PL intensity is four times larger than for another σ+ light polarization, when electrons have antiparallel spins. The absorption band shapes are determined in the Faraday geometry for magnetoexcitons with ne = nh = 0. The width of the bands equals to the magnetoexciton ionization potential. Both band shapes monotonically decrease with maximal heights at the low energy edges. The stronger absorption band decreases linearly and the weaker absorption band decreases faster with exponentially vanishing tail near the high-energy edge.